1. Technological Field
The inventive technology generally relates to a display device employing organic light emitting diodes (OLEDs). More particularly, the inventive concept relates to a scan driving unit, and an OLED display device having the scan driving unit.
2. Description of the Related Technology
Recently, OLED technology has been widely used in flat panel display devices. Generally, an OLED display device implements (i.e., displays) a specific gray level using a voltage stored in a storage capacitor of each pixel circuit (i.e., an analog driving technique). However, the analog driving technique may not accurately implement a desired gray level because the technique uses the voltage (i.e., an analog value) stored in the storage capacitor of each pixel circuit.
To overcome these problems, a digital driving technique has been suggested for such devices. Specifically, each frame is produced by displaying a plurality of sub-frames. That is, one frame is divided into a plurality of sub-frames, where the emission time of each sub-frame is varied (e.g., by a factor of 2), and implements a specific gray level based on the sum of emission times of the sub-frames.
Since the technique displays one frame by display of a plurality of sub-frames (i.e., a scan time is relatively short), a scan driving unit of such device needs to operate at a high speed. Furthermore, these devices may employ a random scan digital driving technique. In this case, a scan driving unit is often implemented by a decoder-type internal circuit to randomly perform scan operations, where the decoder-type internal circuit includes a pre-decoder block and a final-decoder block.
Here, since logic signals output from the pre-decoder block that is located outside a display panel is input to the final-decoder block that is located inside the display panel, a plurality of signal-lines for transferring the logic signals from the pre-decoder block to the final-decoder block are arranged in an outer region of the display panel. Thus, as the resolution of the display panel increases, the number of the signal-lines that are arranged in the outer region of the display panel is greater. This can result in a large “dead space” of the display panel that increases its overall size.